If you are one of the slowly but surely growing base of OS X users, Apple today released a bunch of patches to fix you up. Mac OS X 10.5.3 has been released and the updates are now available through Apple's site, and of course through Software Updates. The patches include fixes for various programs including Time Machine and AirPort. There were various minor updates including some GUI updates, and anyone experience reliability issues with wireless will appreciate the AirPort fixes.
If you aren't automatically updating, don't forget to retrieve them. We've all heard enough stories about flaws being discovered that result in thousands of system compromises and infections.